Iontophoresis has come into increasing attention as an effective method for the application of drugs through the skin.
In practice, the process of iontophoretic drug delivery is typically achieved by placing an ionic drug either in solution or in gel form on a carrier and placing the drug-containing carrier into contact with the skin. A pair of electrodes is placed in contact with the skin and with the carrier. Direct current is applied between the two electrodes. Under the influence of the electric field present, drug molecules migrate through the skin. As current flows between the two electrodes placed at spaced apart locations on the skin, the current path carries the drug with it.
Delivery of a drug to the patient iontophoretically may be accomplished either at a constant rate over a long period of time, or periodically at various intervals and in some situations, upon demand. As can be seen, it may be necessary for the drug-containing carrier to be maintained in contact with the patient's skin over a long period of time, either for continuous drug delivery, or to permit frequent interval delivery over a period of time.
The iontophoretic delivery system may include a drug-containing carrier such as an adhesive patch and a controller having a source of electrical power and which is connectable to the patch for providing the necessary electrical current to deliver the drug. While effective devices are available for both providing a drug-containing patch for disposition on the skin of a patient and an electrical power source for applying iontophoretic effecting currents, oftentimes these devices remain connected to the patient even when iontophoretic delivery is not being effected.
In order to deliver a drug to the patch, the patch may be adhesively applied to the patient and the controller is attached to the patch. Oftentimes the controller is as large as, or larger than, the patch. It also should be somehow secured in place on the patient so that the patient may remain mobile and carry both the patch and controller with him as he moves about.
One of the problems with a transdermal drug delivery device such as described above, especially one that is compact and portable to provide patient mobility, is how to attach the controller to the patient and yet be as unobtrusive as possible and comfortable for the patient. A side-by-side arrangement of patch and controller may occupy too much space on the patient's skin and limit the choices where the transdermal device may be attached to the patient. Also, the controller may then have to be fastened to the patient's skin by adhesive or a strap, for example, which may be uncomfortable to the user.
Also, it is envisioned that the controller, which may contain sophisticated electronics besides just a power source to control and monitor the delivery of drug to the patient, is repeatedly used while the patch is discarded after use and replaced with new patches. The replaceable patches and controller should be so structured as to make it easy and convenient for the patient to replace used patches with new patches on the controller.
In situations where the periodic delivery of the drug is indicated, there is no need to maintain the source of electric current connected to the patch between doses. While the unobtrusive drug-containing patch may remain with the patient, removability of the current source would permit the patient to be free from cumbersome connection to the current source between doses. At such time as iontophoretic delivery of the drug is necessitated, the drug-containing patch attached to the patient's skin may be reconnected to the current source. However, to assure that the drug is administered properly, connections between current source and the patch must be reliably maintained.
It is therefore desirable to provide an interconnection assembly which permits the reliable interconnection between a drug-containing patch, positionable on the skin of a patient, and a source of electrical current for permitting iontophoretic delivery of the drug.